When a puncture occurs in a tire, a puncture sealing agent is frequently used. The sealing agent is an agent which is introduced into the tire to seal up the punctured portion from the inside, thereby ensuring the airtightness of the tire so that the tire can be refilled with air.
Puncture sealing agents are known of the type in which a rubber latex is blended with at least an anti-freezing agent. The anti-freezing agent of this known puncture sealing agent may be ethylene glycol or propylene glycol. However, when this known puncture sealing agent is stored for a long term, the rubber particles or adhesive agent particles therein aggregate near the surface so that the sealing agent tends to be transformed into a creamy material. The creamy material clogs the outlet of a tire sealant container hindering the passage of the sealing agent out of the contained into the tire so that smooth puncture sealing operation cannot be carried out.
The creamy material is presumably generated by the following mechanism: in the puncture sealing agent, which is a latex wherein rubber particles and adhesive agent particles are dispersed and floating in an aqueous ethylene glycol solution by ionic repulsive force between the particles and a surfactant, the gravity of the dispersed particles is smaller than that of the aqueous ethylene glycol solution, which is a medium; therefore, the respective rubber particles gradually rise up (float up) in the medium by the action of gravity and the rising particles form a particle-concentrated layer near the surface, whereby the puncture sealing agent is transformed to the creamy material. Thus, it is desirable to provide a puncture sealing agent that overcomes this problem and limitation of the typical puncture sealing agent and it is to this end that the present invention is directed.